MTS to MTS Converter

MTS to MTS — Same Extension, Different Insides

.mts is the on-card filename AVCHD camcorders use — the format Sony and Panasonic introduced in 2006, wrapping H.264 video and Dolby Digital audio inside an MPEG-2 transport stream. Card-full recordings arrive at 17-24 Mbps for 1080p, which is generous for a tape-replacement format and unwieldy for everything afterwards.

A same-format pass keeps the extension while changing what is inside: bring a 24 Mbps original down to a size you can actually move, drop 1080p to 720p, re-encode a Dolby Digital track to something a fussy editor will accept, or cut the dead frames off the front and back of a clip. It is a real re-encode on our servers — there is no copy-through option — so it costs a generation of quality and it is not a way to rebuild a card. Uploads travel over an encrypted connection and are deleted automatically after a few hours. No sign-up, no watermark.

How to Re-encode an MTS File

1. Upload Your MTS File: Drag and drop, or click "+ Add Files". On an AVCHD card the clips live under PRIVATE/AVCHD/BDMV/STREAM/ with names like 00001.MTS; copy them off first, then upload. Batches share one set of settings.
2. Pick a Video Codec: H.264 is preselected, which matches what the camcorder recorded and is the right answer for almost every job. H.265 is also offered and roughly halves the size at matched quality; DivX, Xvid, MPEG-4, MPEG-2 and MPEG-1 exist for old hardware and are a poor fit for HD footage.
3. Pick an Audio Codec: AAC is preselected. AC3 is the one to choose if the file has to stay AVCHD-compatible or feed a Blu-ray authoring tool — see the table below. EAC3, DTS (DCA), MP2 and MP3 complete the list.
4. Set Compression, Resize, Trim, then Convert: File Compression opens on Quality Preset at "Very High (Recommended)", which on H.264 resolves to CRF 18 — near-lossless and a good default for a single re-encode. Specific file size takes a megabyte figure; Constant Quality exposes the CRF slider directly on a 16-51 scale opening at 23. Video resolution starts on Keep original. Trim takes a start time and duration. Click Convert and download.

Our .mts vs a Camcorder's .mts

Measured on the output this page produces, not inferred from the spec.

The framing distinction is worth pinning down because it trips people up: .m2ts output gets 192-byte BDAV framing with a four-byte arrival-timestamp prefix, while .mts and .ts get plain 188-byte packets. The extension decides. If a Blu-ray authoring tool insists on BDAV framing, MTS to M2TS is the page that produces it.

Audio Codec Choices and AVCHD Legality

The default AAC track is the reason a converted .mts will not simply drop back into an AVCHD authoring project. Switch to AC3 and that objection goes away, though the file still is not a disc structure.

Frequently Asked Questions

Can I put the converted file back on my camcorder's SD card?

No. AVCHD is a folder structure, not a single file: the camcorder expects PRIVATE/AVCHD/BDMV/ with STREAM, CLIPINF, PLAYLIST and index files that reference each clip and describe it. Dropping a loose .mts into the STREAM folder leaves the index inconsistent and the camera will not list it. Authoring software can rebuild that structure from your converted clips; a converter cannot.

Why is my file smaller after a "same format" conversion?

Because the codec is the same but the encoder is not. A camcorder encodes in real time inside a power budget, so it spends bitrate generously — often 24 Mbps at 1080p. x264 running offline at CRF 18 reaches comparable perceptual quality at a fraction of that. You still lose a generation of detail, but the size drop is genuine rather than an illusion.

Does MTS to MTS lose quality?

Yes. There is no stream-copy path on our servers, so the video is decoded to frames and re-encoded on every job. The default "Very High" preset maps to CRF 18 on H.264, which is close to visually lossless, but a second generation of lossy compression is never free. Do your trimming, resizing and audio change in a single pass rather than converting repeatedly.

My camcorder footage is interlaced. Will the conversion fix the combing?

No. There is no deinterlacing step anywhere in this pipeline, so 1080i footage keeps its field structure and the comb artefacts stay in the frames exactly as they were. Deinterlace locally before uploading if progressive output matters, or shoot progressive next time — most AVCHD camcorders offer a 1080p mode.

Why do my clips come in several files that end abruptly?

That is the FAT32 file-size limit, not a fault. AVCHD cards are typically FAT32-formatted, so recordings are split at just under 4 GB — roughly 20 minutes at the top 1080p bitrate — and the camera writes 00001.MTS, 00002.MTS and so on. Each converts independently here. To rejoin them into one continuous clip you need a merge tool rather than a converter.

Should I convert to MP4 instead?

For almost every purpose, yes. MTS to MP4 does the same H.264 encode into a container that browsers, phones, smart TVs, iMovie, CapCut and every upload form already understand, whereas .mts opens in almost nothing without help. Stay on MTS only when a workflow, an archive naming scheme, or an authoring tool expects the transport stream.

What is the difference between MTS and M2TS?

They are the same transport-stream family with different framing and different origins. .mts is what the camcorder writes to the card; .m2ts is what appears after importing to a computer or on a Blu-ray disc, and it uses 192-byte BDAV packets — a four-byte arrival timestamp prefixed to each 188-byte TS packet. Our output follows the extension: .mts gets plain 188-byte packets, .m2ts gets the BDAV framing.

Can I trim the dead frames at the start and end of a clip?

Yes, and this is one of the better reasons to run a same-format pass. The Trim control takes a start time and a duration, and because the file is fully re-encoded the cut lands exactly where you set it rather than snapping to the nearest keyframe. No black frames, no audio offset. For interactive scrubbing on a longer recording, Video Cutter gives you a timeline instead.

Is there a shortcut if I only want the file smaller?

Compress MTS is that shortcut. It opens on a "Target file size (%)" slider — a control this converter deliberately hides — so "make it 50% of the size" is one action. Come back here when you also need to change the codec, the audio track, the resolution or the running time.

How long do you keep my uploads?

Files and their outputs are deleted automatically after a few hours. Nothing is shared or made public, and no account, email address or payment is required to use the tool.